Major Research Areas

Upstate boasts basic and clinical researchers with diverse expertise in neuroscience, molecular genetics, genomics, epigenetics, structural biology, infectious disease, and behavior disorders. This allows students the opportunity to perform research in a wide range of research areas and easily collaborate when new expertise is needed.

Current Hospital Privileges

Publications

Link to PubMed (Opens new window. Close the PubMed window to return to this page.)

Research Abstract

Specific areas of research in the laboratory

Molecular biology of autoantigens:

I. Expression of Human Endogenous Retroviral Sequences (ERS). ERSs and other retrotransposable elements are a major factor in shaping, reorganization, and evolution of the eukaryotic genome. The notion, that aberrant structure, expression or recognition of ERS is involved in the pathogenesis of autoimmunity, could explain both the familial aggregation and detection of cross-reactive anti-retroviral autoantibodies in patients with autoimmune diseases. HRES-1, an endogenous retroviral element that has entered the human genome at the developmental stage of old world primates, has been cloned in this laboratory. The HRES-1 genomic locus has been mapped to a common fragile site on the long arm of human chromosome 1. It is transcriptionally active, and contains two open reading frames. In contrast to most nuclear aut oantigens which are ubiquitously present in every nucleated human cell, HRES-1/p28 is expressed in a tissue-specific manner (Proc. Natl. Acad. Sci. USA, 89:1939-1943, 1992). Antibodies to HRES-1/p28 are detectable in patients with systemic lupus erythematosus and overlap syndromes (Arth. Rheum. 38:1660-1671, 1995). Future studies on HRES-1 will 1) determine the role of genetic variations of the HRES-1 gene locus in autoimmune diseases, 2) delineate the molecular basis of its tissue-specific expression 4) assess HRES-1 autoantibody levels and expression in association with disease activity.

A novel retrotransposable element was cloned based on a limited sequence homology to the endogenous retroviral sequence, HRES-1. This repetitive element was found to constitute exons 2 and 3 of the coding sequence of a 38 k D autoantigen which corresponds to the human transaldolase (TAL-H) enzyme. Detection of a retrotransposon, TARE (transaldolase-associated retrotransposable element), in the coding sequence of a human gene demon strates the importance of these repetitive elements in evolution of the eukaryotic genome. Ongoing studies are focused on mobility of TARE and its role in transcriptional regulation of the TAL-H gene. TAL is a key enzyme in the nonoxidative phase of the pen tose phosphate pathway (PPP) which fulfills two essential functions, formation of ribose 5-phosphate for synthesis of nucleotides, RNA, and DNA and generation of NADPH for biosynthetic reactions and to maintain glutathione at a reduced state, thus, to protect sufhydryl groups and cellular integrity from oxygen radicals. Importance of PPP in general, and of TAL in particular, have been demonstrated in numerous processes involving programmed cell death (PCD), e.g. host defence mechanisms against oxidative stress, inflammation, lymphocyte activation, phagocytosis, embryogenesis, myelination, and extreme sensitivity of oligodendrocytes to PCD. The role of TAL-H in PCD is curre ntly being evaluted by gene transfection studies. Molecular biology and autoantigenicity of TAL is particularly significant in patients with multiple sclerosis (MS). MS is caused by demyelination secondary to a selective loss of oligodendrocytes by immune-mediated PCD. Molecular mimicry between viral core proteins and the TARE-encoded segment of TAL-H may play a role in breaking immunological tolerance and leading to a selective destruction of oligodendrocytes in MS.

Apoptosis is a fundamental form of programmed cell death (PCD) which is indispensable for normal development and maintenance of homeostasis within multicellular organisms. Defects in apoptosis may underlie the etiology of n eurodegenerative diseases, cancer, autoimmune diseases, and the acquired immune deficiency syndrome (AIDS). In particular, apoptosis is blocked at various levels in cancer cells. By contrast, increas ed apoptosis underlies the etiology of T cell depletion in AIDS. Reactive oxygen intermediates (ROIs) have long been considered as toxic by-products of aerobic existence, but evidence is now accumulating that controlled levels of ROIs modulate cellular function and are necessary for signal-transduction pathways, including those mediating apoptosis. Transaldolase (TAL) is a key enzyme of the reversible nonoxidative branch of the pentose phosphate pathway (PPP) which is responsible for generation of NADPH to maintain glutathione at a reduced state (GSH) and, thus, to protect cellular integrity from ROIs. To evaluate the role of TAL in this process, Jurkat and H9 human T cells were permanently transf ected with TAL expression vectors oriented in the sense or antisense direction. Overexpression of TAL resulted in a decrease in G6PD and 6PGD activities and NADPH and GSH levels and rendered these cells highly susceptible to apoptosis induced by serum deprivation, hydrogen peroxide, nitric oxide, tumor necrosis factor (TNF), anti-Fas monoclonal antibody or infection by HIV-1. In addition, reduced levels of TAL resulted in increased G6PD and 6PGD activities and in creased GSH levels with inhibition of apoptosis in all systems. Our results provide definitive evidence that TAL has a role in regulating the balance between the two branches of PPP and its overall output as measured by GSH production and thus influences sensitivity to cell death signals. The effect of TAL expression on susceptibility to apoptosis through regulating the PPP and GSH production is consistent with an involvement of ROIs in each pathway tested. Currect efforts are directed towards TAL-mediated regulation of metabolism and specific cell death programs.

IV. Mitochonrial hyperpolarization (MHP) is an early and reversible event in T cell activation and apoptosis

Disruption of the mitochondrial transmembrane potential (MTP) has been proposed as the point of no return in apoptotic signaling. MTP is dependent upon the electron transport chain transferring electrons from NADH to molecular oxygen and proton transport mediated by the F0/F1 -ATPase complex. The energy stored in the electrochemical gradient is utilized by F0/F1 -ATPase to convert ADP to ATP during oxidative phosphorylation. We have discovered that elevation of MTP or MHP occurs in the early phase of Fas-induced apoptosis of Jurkat human leukemia T cells and normal human PBL. MHP precedes phosphatidyl serine (PS) externalization and disruption of MTP in Fas- and H2O2 -induced apoptosis. These observations were confirmed and extended to p53, TNF, and staurosporin-induced apoptosis by other laboratories. Elevation of MTP is independent from activation of caspases and represents an early event in apoptosis. With MHP and extrusion of H+ ions from the mitochondrial matrix, the cytochromes within the electron transport chain become more reduced which favors generation of ROI. ROIs can modify signaling initiated via the CD3/CD28 receptors. Moreover, T cell activation via CD3/CD28 receptors induces mitochondrial hyperpolarization and ROI production in normal PBL. Recent data from our laboratory suggest that T cell activation-induced MHP is mediated by Ca2+- and redox-dependent production of nitric oxide.

V. Activation and Cell Death Signaling in Systemic Lupus Erythematosus

We have discovered that lymphocytes from patients with SLE exhibit mitochondrial hyperpolarization, leading to abnormal activation and cell death signaling. Mitochodnrial hyperpolarization (MHP) leads increased production of reactive oxygen intermediates, cytoplasmic alkalinization, and ATP depletion which in turn predisposes to necrosis in response to activation and cell death signals. Understanding the molecular basis of MHP may lead to novel therapies in patients with SLE.

Blank, M., Shoenfeld, Y. and Perl, A. (2009) Cross-talk of the environment with the host genome and the immune system through endogenous retroviruses in systemic lupus erythematosus. Lupus, 18: 1136-1143.